1466

class Solution {
public:
    int minReorder(int n, vector<vector<int>>& connections) {
        vector<int> graph[n];
        for(auto edge: connections){
            graph[edge[0]].push_back(edge[1]);
            graph[edge[1]].push_back(-edge[0]);
        }
        bool vis[n];
        memset(vis, 0, sizeof(vis));
        int ans = 0;
        queue<int> q;
        q.push(0);
        vis[0] = true;
        while(!q.empty()){
            int curr = q.front();
            q.pop();
            for(int next: graph[curr]){
                if(!vis[abs(next)]){
                    vis[abs(next)] = true;
                    q.push(abs(next));
                    ans += (next>0);
                }
            }
        }
        return ans;
    }
};